Code
U0128
Generic
U — Network/User
Lost Communication With Park Brake Control Module
Views:
UK: 22
EN: 136
RU: 38
AI status
Completed
Completed
100%
Causes
- Blown fuse or loss of module power/ground
- Loose, corroded, or damaged connector at park brake module
- Open/short in CAN bus wiring (CAN High/Low)
- Faulty park brake control module
- Bus termination resistor missing or failed
- Software/configuration error or module programming issue
Symptoms
- Electronic parking brake inoperative or stuck in service mode
- Instrument cluster warning lamp or message related to parking brake or communication
- Push-button park brake does not operate or is intermittent
- Multiple modules reporting communication errors or bus faults
- Stored U0128 and possibly other U0xxx communication codes
What to check
- Retrieve all network codes and note time stamps and freeze-frame data
- Scan for presence of the park brake module on the network with a scan tool
- Visually inspect module connector for corrosion, bent pins, or damaged sealing
- Check related fuses and relays for continuity and correct voltage
- Measure battery voltage at module connector with ignition on
- Check for other U0xxx codes that indicate broader CAN bus issues
Signal parameters
- CAN bus voltage (CAN High and CAN Low) at module connector
- CAN bus differential voltage (idle ~2.5V, CAN_H ≈ 2.5–3.5V, CAN_L ≈ 1.5–2.5V)
- Bus-off / TX/RX error counters from scan tool
- Module presence/identifier (module responds to tool queries)
- Park brake module status / state PIDs if available
- Supply voltage and ground circuit measurements at module
Diagnostic algorithm
- Connect a professional scan tool and read all network DTCs. Record U0128 and any related codes.
- Attempt to communicate with the park brake control module. Note whether the module is present or non-responsive.
- Inspect the park brake module connector and wiring for damage, corrosion, bent pins, or poor sealing. Repair as needed.
- Check all fuses and power feeds for the module. Verify battery voltage at the module with ignition on. Verify a solid ground connection.
- With the ignition on, measure CAN High and CAN Low voltages at the module connector. Compare to expected idle values and check for short to battery/ground.
- Check CAN bus termination resistance (typically ~60 ohms across CAN_H and CAN_L with ignition off). Repair open/incorrect termination or wiring faults.
- If wiring and power/ground are good, inspect for other modules causing bus errors. Disconnect suspect aftermarket devices or modules that may be loading the bus.
- If available, follow manufacturer-specific procedures to reprogram or reset the park brake module. Reflash or reflog only per service manual guidance.
- If communication still fails and wiring/power are confirmed good, consider replacing the park brake control module. Verify proper programming/coding after replacement.
- Clear codes and verify repair by confirming reliable communication and normal operation during a functional check or road test.
Likely causes
- Fuse or power/ground problem at the park brake module
- Poor connector contact or wiring damage at the module
- CAN bus wiring open, shorted, or poor termination
- Park brake control module internal fault
Fault status
Status
Lost Communication With Park Brake Control Module
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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